


Not An Advantage

by Book7BrokeMyBrain



Category: Sherlock (TV), Sherlock Holmes & Related Fandoms
Genre: Chan, Extremely Dubious Consent, Frottage, Infidelity, Intercrural Sex, M/M, Post-Hiatus, Sibling Incest
Language: English
Status: Completed
Published: 2013-12-18
Updated: 2013-12-18
Packaged: 2018-01-05 01:06:36
Rating: Mature
Warnings: Underage
Chapters: 1
Words: 4,536
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1087771
Author URL: https://archiveofourown.org/users/Book7BrokeMyBrain/pseuds/Book7BrokeMyBrain
Summary: <blockquote class="userstuff">
              <p>If anyone is going to teach his little brother about sex, it ought to be him, because someday he might need to know how.</p>
            </blockquote>





	Not An Advantage

**Author's Note:**

  * For [bivouac](https://archiveofourown.org/gifts?recipient=bivouac).



> Beta'd by asnowyowl. Thank you. Any remaining errors are my own.   
> Case based on The Adventure of the Devil's Foot 

“You haven't managed to kiss anyone yet, have you?” Mycroft stands in the doorway to Sherlock's room. Sherlock is flopped on his bed, trying very hard to ignore his insufferable brother. “Fifteen. You are fifteen, almost sixteen. I told you the last time we were home what you needed to do.”   
Sherlock rolls over, closes his book. “You are not my teacher. I don't accept assignments from you. Now, go away.”   
Mycroft, looking priggish in his hacking jacket, steps in the room, closes the door, and clasps his hands. “I warned you. There are things you need to know – life skills – basic, human interactions you need to master if you ever hope to rise in this world like I will.” His smile is condescending and arrogant, but not without justification. “You are running out of time.” He steps to the bed, sits alongside Sherlock's hip.   
“I told you I have no interest, Mycroft! Leave it alone. I don't need to know anything.”   
“You aren't unattractive, you know. I'm sure you'll grow into your limbs and features someday. And when you do,” Mycroft brushes the fringe from Sherlock's brow, sweeps his fingertips along his jaw, “you will want to be able to use the attention you will get to your advantage. At the very least, you ought to have seduction as part of your considerable arsenal, my dear. Believe me, university will be a test.” He runs his thumb across Sherlock's plump lower lip. “Sex can help you make – and keep – important contacts.”   
“I'm not climbing anything. I don't want a government position, and I don't want anyone. And I'm not your 'dear',” Sherlock adds petulantly.   
“This is not like eating your broccoli, brother. This is something you must do.” Mycroft takes a breath. “We are alike, you know that. Take advantage of my experience.” Mycroft leans in, holding Sherlock's chin. “Today's lesson: the kiss.”   
He presses his lips softly against his brother's, just briefly, before sinking in more deeply. He withdraws and cocks an eyebrow. “Not so horrible, is it?”   
Sherlock shrugs a shoulder. “How much longer until we're finished? I have reading.”   
“Until I see the lesson has sunk in.”

* * *

The bowl of water on the stand steamed in the chill morning as John leaned over it, gingerly squeezing out his towel, pressing it against his face, softening his stubble. The large Cornish guest house they'd booked into had no _en suites_ , only shared baths, but they were very generous with the hot water. It was a bit of an adventure, a throwback to simpler times, to shave at a stand in front of a mirror in the middle of one's bedroom. Hardly an inconvenience.  
He lathered up, then drew his razor with a practiced hand up his throat, down his upper lip and cheeks, carefully around his chin and sideburns. Scrape, scrape, scrape in the silence of the morning. John was content, although he hadn't quite worked out the used water/clean water issue. He finally poured clean from the ewer onto his towel, burning his fingers, in order to wipe the residue away.  
His phone buzzed. He ignored it.  
Sherlock entered the room, terry robe on, blotting his hair with a towel. He dropped his toiletry bag on his bed.  
“Good shower?” John inquired.  
“Quite.”  
“Long line?”  
“No.”  
John frowned a little. “Peak morning hour before breakfast and no line?”  
Sherlock cleared his throat. “I may have said something to the people before me.”  
John sighed as he dropped his things back into his kit. He used the warm towel to wipe his underarms and chest. “No one is going to talk to us in the breakfast room, are they?”  
“Probably not.”  
“Terrific.” His phone buzzed again. “Rather counterproductive, if we are supposed to be probing for information.”  
Sherlock began to dress, back to John. “It was expedient. We have things to do today.” He tugged on his pants under his robe, then his trousers, then shirt, keeping himself covered against the cool air as long as possible. “Has Mary not gotten to the silently fuming stage yet?” Sherlock sat on the edge of the mattress tugging on his socks, watching John dress.  
“I could murder a full English this morning,” John replied, buttoning quickly.  
“If she's still texting, then either she's not that angry that you came with me, or she's furiously angry, and she's going to leave you.”  
“And some nice strong coffee. I think I'm going to need it today.” He bent down to tie his shoes. “And it wasn't expedient, because now we have to work against the ill will you created when you said God-knows-what to those nice people. No one will trust you.”  
Sherlock smiled. “Ah. But they'll trust you. Besides, it's the locals we care about, not the tourists, and I didn't offend any of those.”  
John shook his head. “Shall we?” He gestured Sherlock out the door to start a very long day.

* * *

Mycroft finds him, after quite a bit of looking, in the greenhouse. He is puttering with a tray of young foxgloves.  
“We had an appointment.”  
“I never agreed to that.” Sherlock plucks a tiny weed from between the flower stalks.  
Mycroft sidles up behind his little brother, looming. Sherlock grips the edge of the potting bench.  
“You know I worry about you, constantly. I always will.” He strokes the back of Sherlock's head, like a pet, toying with the curling lengths. He drags a fingertip across the nape of his neck as Sherlock stiffens in place. “We are different. Apart. Better, I dare say. And there is nothing more frightening to the average than the exceptional.” He slides his palm around Sherlock's hip, down to cover his fly. He rubs softly, tracing the flesh he finds as Sherlock writhes subtly. Sherlock drops his head and Mycroft mouths his long neck. He whispers, “Learn how to assimilate.”  
He turns his brother, bottom pressed against the bench, opens Sherlock's flies and pushes down his trousers. Mycroft hikes his trouser legs, takes a knee and lifts Sherlock's barely turgid flesh from his pants. He strokes it, flicking his fingers over the head with every pass, making the boy gasp. He hardens quickly, then.  
Mycroft looks up and takes Sherlock into his mouth. Sherlock frowns in concentration, leaning back, head tipping. Mycroft falls to it, sliding, sucking, teasing. Sherlock begins to quiver and Mycroft speeds up to finish him off. Sherlock curls forward, convulsing, gasping, hands clutching his brother's fine hair, and comes in his mouth.  
He pants for a few moments as Mycroft pulls away and dabs firmly at the corners of his mouth with his handkerchief. He stands and brushes off his knee. He deftly tucks Sherlock back into his clothes.  
“Remember what I just did. All of it. It's your turn, next time.”

* * *

“Mary! Listen!” John paced around outside the cottage where the bodies had been found days before, phone to his ear. “No. I thought this was settled.” He paced, not seeing Sherlock hovering in the front door. “Literal life and death situation. I told you. A whole family, and another has just died.” He clenched his jaw. “You knew I was a doctor when you married me. Yeah, well you knew Sherlock was alive before you married me, too. You _knew –_ ” He turned in a circle. His voice went quiet. “Right. Then you should have forfeited the deposits on the hall and sent back the gifts. It'd come out cheaper than a lawyer.” He slid the phone shut and shoved it into his inside pocket. He caught Sherlock's eye and pointed a finger in warning. “Not a word.”  
Sherlock held up two palms in surrender, and led him inside.  
They let themselves in past the crime scene tape, into the closed parlor. A game of Cluedo lay open on the table, apparently in the early stages of play. Yellow tape on the tabletop and chair indicated where the one living victim was found before he was taken to hospital. His sister's and brother's bodies were long ago photographed and removed.  
Sherlock danced slowly around the room, arms crossed, then reaching, then crossed again, imagining the victims' movements before death.  
“The lone survivor sat here. Nearest the window, which was open slightly. The sister and other brother sat across, next to the heater. It was a chilly night, but the one brother may have found the heat stifling.” Sherlock paused his movement and turned to John. “You mustn't blame yourself. It was only a matter of time.”  
John shook his head. “I'm sorry. What?”  
“Mary. Your marriage. It was inevitable once you started working with me again. It's not your fault.”  
“I just told you 'not a word'.”  
“Ah. So you did.” Sherlock clapped his hands and turned back to the room. “I suspect a toxin, airborne. I have a theory about the delivery system.”  
“You are unbelievable.” John left angrily, which was fine with Sherlock, as he had something rather illegal to do.  
He squatted down next to the heater and pulled the grating off the front. He pulled a glassine envelope from his inner pocket along with his pen knife, and scraped some white residue from the coils into it. He found grains of darker powder, probably as yet unactivated by the heat. Possibly very dangerous. He collected that as well, and slipped the sealed specimen back into his coat.

* * *

Today's assignation is in Mycroft's room. He's come down for Christmas and freed an afternoon for the lesson.  
He lays Sherlock out, nude, on the bed: white skin, dark hair, white cotton. Mycroft undresses, but puts on his quilted robe. He lies next to his brother and strokes his skin all over. He flicks the edge of his robe across Sherlock's legs to keep him warm, rests his hand on his belly.  
“You're having a growth spurt. Soon you'll be as tall as I. So handsome,” he muses fondly. Sherlock remains mute. “Have you kissed anyone yet? Or done anything else?”  
Sherlock rolls his eyes. “No. I told you these lessons are a waste of time. I don't want that from anyone.”  
Mycroft caresses his face, traces the line of his nose. “Someday you may. No, listen. Someday you may meet someone. I want you to be prepared. I want my brother to have anything and anyone he wants from this world. Trust me. Please. Someday you may feel differently.”  
“Someday?” Sherlock asks, doubt creeping in.  
Mycroft nods, and rolls over to kiss his brother. They apply themselves to the lesson.  
Mycroft positions him again and again. On their sides, spooning, he thrusts between Sherlock's thighs, then reverses to allow the boy his turn. He scolds him to keep him from coming too soon. He bends Sherlock in half, legs together, lays atop him and ruts against his perineum, into the gap of his thighs. They both enjoy that very much. With Sherlock prone, he thrusts up the cleft of his buttocks. Sherlock actually shivers with pleasure as Mycroft's cock glides against his anus, over and over. He clutches the sheets and humps into the mattress, pressing his forehead into the pillow. Mycroft counts it as a victory when he makes his brother come that way. He fucks down between his brother's thighs to finish himself off.  
Both sated, they recover silently, then get dressed for dinner with Mummy.

* * *

“Isn't drinking by oneself in the middle of the day supposed to be a bad sign?” Sherlock slid in next to John on the settle before the fire in the B&B. John sipped on his large whiskey and tried to ignore him. “When I met Mary I was surprised she was blonde. You reverted to type. Regressed in my absence.”  
John sighed. “What are you talking about? Regressed from where?”  
“Obviously, you didn't notice your pattern. Actually, I wouldn't have been surprised if I'd returned and you'd been with Mycroft.”  
“ _Mycroft?_ What the hell does that mean?”  
“He'd be the closest you could get to having me. He's my blood. General size and shape. Intelligent. Common history.”  
John glared, glassy eyed. “I hated Mycroft. For what he did to you. He spilled your life story to a madman out of vanity. He practically killed you himself. Why in god's name would I want him? And he's a man.”  
“Oh, the parts don't matter,” Sherlock dismissed that detail with a flick of his hand. “When we first met, you dated women who looked like you: short, blonde. As we progressed and you became more attached to our life, our work, that changed. Who was the last woman you were with? Jeanette. Tall, dark, smart, mean to you.”  
“Oh, my god.”  
“You see now. It's not your fault. You didn't know your own mind.”  
“Christ. Could everyone see that? No wonder I got such pitying looks from the Yard and everyone, after....” John polished off his drink. “Jesus, that's... humiliating.” John clutched his empty glass. “God, _the wedding_. You were my best man. Was everybody laughing at me behind my back?” He sank his head down into his hand.  
Sherlock frowned in thought. “I don't think so.”  
“Oh, god, they were.” John stood unevenly. “I can't – ”  
“John, wait.” Sherlock grabbed his sleeve, pulled him closer. “John. You chose me. Over and over, you chose me.”  
“I chose the work.”  
“Same thing. I am the work. I am this life. I know what you were like when I was gone.”  
“I was boring,” John murmured. “I missed you.”  
“I missed you, too.”  
“Did you?” John's face crumpled slowly into grief.  
“Of course I did. John.” Sherlock tightened his grip on John's jacket. “I chose you, as well. I've never chosen anyone before.”  
John frowned, shook his head. He tracked Sherlock's ascent as the man stood. “So stupidly tall.”  
Sherlock placed his hands on John's shoulders, leaned down and pressed his lips to John's open mouth, open in astonishment. He finished with a lush tug to John's lower lip, and drew away.  
John covered his mouth with his hand, nodding slightly, eyes darting. “I need a lie down.”

* * *

Sherlock is cataloging items and packing for his gap year trip to the Himalayas. He didn't want to go, initially, wanted to continue straight on to University, but he was convinced otherwise. He puts a thick pair of socks in his pack and turns to address his brother who has been haunting his doorway for a minute already.  
“I don't leave for three days.”  
“Yes. I know.”  
“Surely you aren't planning to spend the next three days here. Will you miss me that much?” Sherlock turns back to his packing.  
“Of course I'll miss you.”  
“Miss the chance to boss me around, more like. You can't reach me when I'm in Tibet. God, you're worse than Mummy ever was.”  
“Well. Someone had to be.” Mycroft closes the door and glides up to his side. “And I will have eyes on you as much as my new position will allow. No, I'm here early because we have one lesson left, a rather intense one. You might need time to recover, physically, and I wouldn't want you to be uncomfortable on the long flight. You understand.” Mycroft smiles softly.  
“I understand.” Sherlock looks at him. “What if I told you I'd already taken this step. I don't need you to show me?”  
Mycroft's brow lifts. “I would say you were lying.”  
“And what if I said I didn't want it to be you? I do listen to you Mycroft. Data is data, regardless of the source. What if I believe you that someday....”  
“Sentiment? Is my little brother a romantic after all?”  
“No! It's just – ”  
“Are you so confounded? That's not like you at all. But, here you see how sentiment detracts from the logical. It must be put aside.”  
Mycroft brushes the fringe of curls from Sherlock's forehead. Sherlock shrinks away with a slight toss of his head.

* * *

Sherlock managed half an hour of waiting before he followed John to the room. He found him curled on his side, awake. He tossed his coat on a chair and stood beside him.  
“If you're going to talk to me, sit. I'll get vertigo craning up at you.”  
Sherlock dropped to his knees beside John, leveling the field of vision. He looked uncomfortable, uneasy. Not a look John was used to seeing on Sherlock. And shame, embarrassment were there. Definitely not emotions Sherlock entertained often.  
“I'm not what Moriarty called me. Virgin. I'm not that. Not entirely.”  
John braced up on an elbow. “Sherlock – ”  
“I am limited. I know that. I am married to the work. But you are part of the work.” John covered Sherlock's hand with one of his, steadying him. Sherlock minutely relaxed in relief. “I want to keep you, always. I can offer you my body to make it a complete relationship. If that is the only thing preventing you from putting others aside, then you can have me. I understand that some males are possessive and find taking a partner's firsts quite arousing, so I will tell you that I have never been penetrated – well, orally, yes, but not anally – and I offer that to you, John.”  
“Sherlock!” John gasped, sitting up. “Jesus....”  
Sherlock sat back on his heels, looking terribly fragile. “Was that not good?”  
John sighed heavily. He slid down to the floor and knelt beside him, taking his hands. “Bit not good. But a bit very good.” That got a tentative smile from Sherlock. “It's not the usual way people go about these things, but look who I'm talking to.” John squeezed Sherlock's fingers. “First of all, thank you. To be held in such high regard by you means a lot to me.  
“Secondly, what we have is already complete. Our friendship, our partnership. And sex is not a requirement for a romantic relationship, just so you know. Your body isn't a commodity. I don't want you to offer up sex like it's pulling out the good china.  
“Thirdly, I _am_ married. I can't just abandon that and run back to Baker Street with you, even if I wanted to.”  
“But it's over.”  
“No, it's not.”  
“Yes, it is.”  
“And you would know, would you?”  
“Yes,” he said coolly, “I would. Ask Anderson. Ask Lestrade.”  
John stood, offered a hand up to Sherlock who refused it by springing to his feet as if on a string.  
He straightened his suit. “I'm done here. We can leave as soon as you're packed. I have experiments to run back in London.”  
“Sherlock....”  
“I'll drive. You're still inebriated.”

* * *

Mycroft watches John Watson hobble away on his cane after being politely kidnapped, bribed and intimidated. _This could be the one_ , he thinks.

* * *

John took the stairs at Baker Street two at a time, praying silently that the fool hadn't done what he thought he'd done. _'Testing toxin. Will know shortly. SH'_ is what the text said. They'd concluded that whatever had killed the siblings had done so horribly, and had been inhaled, most likely after being vaporized on the heater.  
John froze in the kitchen entrance, breath knocked out of him. He braced himself against the jamb as he took in the scene. Sherlock lay supine, not far from the table laden with lab equipment, his phone in his hand. The air held the acrid trace of something.  
John let out a terrified cry of dismay, and threw himself on the floor next to Sherlock. Bent over the body, his fingers flew to find the pulse in his neck, his wrist. It was there, but slow. “Not again, not again, not again,” he chanted as he assessed.  
He grabbed narrow shoulders and shook. “Sherlock! God, Sherlock! Wake up! Are you with me? Please!”  
Sherlock snorted, his eyes flew open. “John!” He reached out and grabbed John's coat. “What's happened?”  
“You poisoned yourself, you idiot!”  
“No, I didn't.”  
“Then why in god's name are you unconscious on the floor?”  
Sherlock sat up, stretched, and stood. John rose with him, keeping his hands on him. “I was sleeping. I was exhausted. The floor was handy. I sent off the sample to the lab for mass spectrometric analysis. There was nothing for me to do but wait, so I decided to sleep. Sent you a text first.”  
John sputtered. “And what's that awful stench?”  
“Ah. Heated up a curry, but left some metal in the microwave.”  
John let out a whimper as he sank his forehead onto Sherlock's chest. He wrapped his arms around the thin torso and squeezed hard. “You utter wanker, doing that to me.”  
Sherlock put his arms around John and held him. “Why on earth would I try out a proven poison on myself when there are perfectly accessible labs around? Ridiculous.”  
“I thought you were dead again.” John calmed in Sherlock's arms. “I thought you were dead.” He rolled his forehead back and forth over Sherlock's clavicle.  
“If you lived here, you wouldn't have been frightened. You wouldn't have let me sleep on the floor, and I probably wouldn't have burned the curry, because you would have heated it up.”  
John tipped his head back, shaking sense into the idiot with his hands fisted in the folds of shirt at his shoulder blades, pulling him closer. “All I could imagine was you dead, with that horrible rictus on your face, or forever insane, and I didn't know what I was going to do.”  
There was a long moment of silence and staring.  
“I think, at this point,” Sherlock rumbled, “I should probably kiss you again because you don't kiss men, and wouldn't take the initiative. And I find that I want to.”  
“That's... very insightful.” John swallowed heavily.  
Sherlock leaned in, paused to lock eyes with John, then took his mouth softly. Their lips clung together briefly until Sherlock pulled away.  
John exhaled a small, high noise. “I'd be lying if I said I hadn't thought about this. After.” He wrapped a hand around the nape of Sherlock's neck and pulled him down again, taking charge of it, heating it.  
They broke apart, panting, hips bumping sideways against the counter top.  
“Sofa,” John commanded at the same time Sherlock offered, “Bed.”  
“I like your idea better,” John said, pulling him down the hallway, quick as he could.  
They rolled on the bed, kissing, touching, reassuring, grasping. Sherlock froze when John cupped his buttocks.  
“All right?” John asked. Sherlock nodded jerkily. “Hey, whatever you want, we can just kiss. I like kissing you. I'm fine with that. I could spend a happy afternoon just having that mouth of yours.”  
“N-no. More. Let's do more.”  
John braced himself over Sherlock's chest. He caressed Sherlock's face from forehead to chin, brushing his forelock to the side. Sherlock stiffened, then relaxed into it.  
“You okay?” Sherlock nodded again, but John was not convinced. “No, you're not. Come here.”  
John slid up to the pillows, ensconcing Sherlock under his arm, encouraging him to drape a leg over John's. He waited. Sherlock seemed to deflate against him. “Sleep.”  
“I'm not – ”  
“You were so exhausted before that you fell asleep where you stood, on the floor. Rest. This can wait.”  
“Aren't you—?”  
“Yeah, that'll go away in a bit.” John wrapped Sherlock up in his arms. “You can wake me up the very best way later. Okay?”  
Sherlock ceased his struggle. John felt him fall asleep literally in moments. He rolled him onto his back, freeing his arm. He lay back on the pillows beside Sherlock and finished unbuttoning his shirt, slipping out of his clothes to lie in his underwear. Much more comfortable. He drifted off gazing at Sherlock's profile.

John woke to tiny kisses peppered along his forehead, around his eyes, beside his mouth. With every kiss came a high little hum, sounding like desperate need. He cringed to realize Sherlock was worshiping every wrinkle, every eye bag, every crease in his skin, the things that made him feel old.   
He cracked an eye. It was late afternoon, going by the light. His eyes popped open to see Sherlock's bare shoulders and arms, bare torso... bare everything. Skin. Lovely.   
Sherlock had his hand up John's vest, feeling his chest. John stripped it over his head. Sherlock grabbed it, tossed it, as John hiked up a hip, hooked his thumb in his briefs and tugged them off. He pulled Sherlock against him. Acres and acres of satiny skin glided against his, alabaster against golden. He couldn't help a sigh and a happy groan as he shifted Sherlock's body on top of his.   
Sherlock took his head between his palms and kissed him fiercely. John smiled and gave as good as he got, lifting his legs to wrap around Sherlock's waist, digging his heels into his bottom. There was a shifting, and suddenly Sherlock stilled, drooping his head to John's shoulder, as he minutely ground down against John's cock, sliding up and down, finding that perfect spot. John reached for his hips and moved him, making it better, adding pressure. Sherlock trembled, began pumping, harder, harder, faster. John felt his bottom clench under his hands, understanding, helped him come along.   
Sherlock shuddered out a low moan as he came. John slipped a hand between them, grabbed his own cock and tugged a few times only, until he crested with the sounds of Sherlock's groaning aftershocks in his ear.   
They lay like that for a minute, panting. When Sherlock started to move off, John locked him in place with his arms and legs. He was not letting him leave, and Sherlock wasn't fighting to go.   
Sherlock languidly turned his face into John's neck, mouthing the skin, pressing kisses up behind his ear, inhaling him, taking him in with every sense he could manage.   
John began to giggle.   
“What?” Sherlock reared back slightly, head still resting on John. “What's funny? Was it bad?”   
“Oh, god, no!” John rubbed Sherlock's back. He giggled again. “It's just that earlier I was afraid you were dead, but I think you almost killed me, just now. Irony. Kind of.”   
“ _Le petite mort_. Let's agree that's the only kind we're allowed.”   
“Agreed.” John kissed him, and rolled them apart. “Ooh. Ugh. Double the cocks means double the mess. Never considered that.”   
Sherlock's deep chuckle shook the bed as John's laugh joined it.

* * *

Mycroft relaxes at his desk sipping an afternoon coffee, watching the CCTV feed of Baker Street. He times his last drop perfectly with John Watson carrying the last of his things inside the front door, and pushing it shut behind him. His brother leaves the window where he has been watching John arrive, no doubt to greet him at the door. Mycroft is thankful there are no more bugs inside the flat, although he regrets having to pull them. Data is data, but TMI is TMI. He shudders minutely.  
He closes the window with the feed, and turns to the file on his desk instead. John's divorce application is currently setting the land speed record for processing time, and will be granted and filed by the end of the work day.  
Mycroft smiles to himself smugly, but not without justification. Never without justification.

The End


End file.
